Introduction
Adsorption isotherms are time consuming and expensive and thus great care is required in sample selection and preparation. Samples for isotherms can be cuttings or core. The most representative samples should be selected at the drill site and sealed immediately in reservoir fluid, if possible, prior to conveyance to the laboratory. If desorption tests are performed prior to adsorption, upon termination of the desorption
test, the sample should be sealed in airtight bags. Exposure of coal samples to air results in loss of moisture and oxidation.
Adsorption analyses can be run on whole core or crushed samples. Although crushing the coal does not significantly (or measurably) change the adsorption capacity of the coal, it does increase the opportunity for oxidation and altering of the moisture content.